In Thailand, land use planning and policy decision-making were—and to some extent still are—organizedin a hierarchical and disjointed fashion. This is also true for the utilization of public lands, including forestreserves in the northern uplands that are often settled by ethnic minorities. There are, however, instancesof change in land policies and regulations and in the way decisions and plans are made. Doi Mae Salong(DMS) in Northern Thailand, where there is a trend towards land use for conservation purposes, is a casein point. This paper aims to explore decision-making by farmers in DMS in the context of changing landregulations and policies from the 1950s to the present. The Institutional Analysis and Development (IAD)framework, together with a historical perspective and with narratives on land management throughtime, were applied by using in-depth interviews of key informants and group farmers’ discussions astools. The time period under investigation was divided into three periods of change: The first period,before the year 1960, was an era of security concern. In contrast, the second period, from 1961 to 1996,was an era of emerging conservation priorities. Finally, the third period, from 1997 to the present, is anera of lessons learned from the conservation era. Land use decision outcomes reveal that the decision-making processes of farmers are influenced both by the hierarchical decisions of higher authorities andby horizontal linkages among multiple stakeholders. However, while farmers participate readily in forestconservation activities, they do not play an active role in the process of changing policies.